A teenage girl, described as “very radicalised”, was arrested after being spotted by French anti-terrorism investigators making “disturbing” comments on the messenger service ‘Telegram’.

The sixteen year old was arrested on suspicion of preparing to carry out an attack on French soil. She was charged with “criminal association in relation to a criminal terrorist enterprise” and “incitement to the commission of terrorist acts by an online communication tool”, and remanded in custody, Le Figaroreports.

The teenager was arrested on Thursday as part of a counter-terrorist operation in Melun, Seine-et-Marne, France. A source informed Le Figaro that “at this stage there have not been any other arrests”.

Searches conducted by elite RAID police officers of the girl’s family home did not uncover any weapons or explosives.

Described as “very radicalised”, the teen was the administrator of a chat group on the encrypted messaging service ‘Telegram’ where she relayed numerous propaganda messages from Islamic State. She also called for the commissioning of a terrorist attack, and expressed her intention to take action, according to the source.

It was through these messages that counter-terrorism was able to track down the minor.

Georges Fenech, Les Républicains Member for the National Assembly (the lower house of French Parliament) and chairman of the parliamentary commission of the inquiry into the attacks of 2015, said the threat was “serious”. He noted the teen jihadi’s use of Telegram, which has been used by various terrorists who have attacked Europe in recent months.

Mr. Fenech, a judge himself, “welcomed the judges’ decision” to place the teenager in custody and her indictment. “In view of the threat, a minor of 16 or 17 years may well be imprisoned. There is no reason to make a distinction based on age, especially as terrorists radicalise more and more young people,” he said.

Though Telegram, a chat service like WhatsApp, is used by millions of ordinary users worldwide, it is frequently cited by authorities as the preferred means of communication between Islamic State militants and their sympathisers because messages are encrypted.

Adel Kermiche and Abdel Malik Petitjean, both 19 years old, communicated via Telegram days before slaughtering Father Jacques Hamel during mass.

This is the latest in a series of ‘teen jihadis’ who have either committed or planned to commit acts of Islamist terrorism across Europe this year.